In operating a film forming operation system such as a CVD apparatus, a PVD apparatus or an epitaxial growth apparatus used in the manufacture of a semiconductor, a solar cell, a photosensitive drum or the like, ClF3 is used as an etching gas.
ClF3 is likely to be adsorbed to a metal, and easily causes a fluorination reaction on a metal surface. Thus, in the film forming operation system such as a CVD apparatus, a PVD apparatus or an epitaxial growth apparatus, ClF3 is adsorbed to a metal constituting a device such as a reaction chamber in the apparatus or a supply passage, thereby causing a reduction in the concentration of ClF3 in the reaction chamber.
Then the present applicant proposed in a prior art document (Patent Document 1) a technique to prevent the reduction in the concentration of ClF3 used during a process, by constructing a gas supply passage using a metal material having a surface on which a coating film of fluoride has been formed.